Vegetation structure and species diversity in Garhjungle sacred forest, West Bengal, India
Abstract
Sacred forest s are traditionally managed forest patches relevant for biodiversity conservation. Vegetation structure of different strata (tree, shrub and herb,) were analysed in Garhjungle sacred forest of lateritic zone in West Bengal. Total 738 woody individuals belonging to 14 species were recorded from random quadrats covering 0.25 ha area. The highest stem density and IVI was obtained by Shorea robusta. All the species had clumped distribution. The trees occupied a basal area of 20.39 m2 ha-1. Species richness and diversity of shrubs and herbs were greater than trees. Presence of various anthropogenic disturbances warrants immediate conservation efforts.
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Introduction
Biodiversity is essential for human survival and economic well being and for the ecosystem function and stability (Singh, 2002). Sacred forests are patches of native vegetation traditionally managed as part of local cultural tradition and functionally link social life and forest management system of a region (Boraiah et al., 2003). The practice of sacred groves dates back to the nomadic hunter-gatherer age of human history (Gadgil and Vartak 2004). At certain places in India such traditional forest management has sustained over the years by native communities (Kushalappa et al., 2001). Sacred groves are believed as treasure house of medicinal and rare plants, as refugia for regional relic flora, and as centres of seed dispersal (Chandran et al., 1998) and are therefore relevant for in-situ biodiversity conservation (Upadhaya et al., 2003). Commonly it is believed that sacred forests are better protected and managed owing to their religious significance and harbour richer plant diversity than other forests. However, several sacred forests are experiencing failure of legal protection in guaranteeing their integrity and conservation (Rawat et al., 2011).
Description of forest vegetation by determining essential measurable properties, such as species richness and biomass, and documenting quantitative relationships among them is a desirable goal of plant ecology (Keddy, 2005). Many studies have documented the community structure, species diversity and regeneration of sacred forests in India. Rao et al. (2011) higher species richenss, diversity and density in sacred forest stands compared with reserve forests in the Eastern Ghats. Sunitha (2002) studied plant biodiversity in the 14 sacred groves of Andhra Pradesh. Higher number of medicinal plants as well as higher success of species regeneration compared to reserve forests has been reported Himachal Pradesh and Western Ghats, respectively (Singh et al., 1998; Boraiah et al., 2003).
The dry tropical forest accounts for 38.2% of the total forest cover of India (MoEF, 1999). Garhjungle forest forms an important part of the tropical dry deciduous forests of the lateritic zone. Lateritic zone in West Bengal comprising Purulia district and western portions of Birbhum, Burdwan, Midnapore and Bankura districts harbor floristically important Northern Tropical Dry Deciduous forests (Champion and Seth, 1968). Lateritic soils are characterized by acidic pH, low NPK content and high iron as reported by many studies (Raychaudhuri, 1980; Chakraborty et al., 2002). Many plants of this region are having immense importance due to their medicinal and dye yielding properties. The minor forest products of the region include lac, sal seeds and leaves, mohua flowers, fibres and flosses, grasses, barks, gums and resins (Mukherjee, 1995). Sacred forests of Garhjungle are very old natural forest and dedicated to goddess Durga.
Forest studies conducted so far in the entire lateritic zone concentrated on floristic and ethnobotanical aspects (Rahaman et al., 2000, 2008; Bhattacharya and Mukherjee, 2006; Bouri and Mukherjee, 2011). Reconstruction of modern vegetation changes using pollen analysis was attempted by Bhattacharya et al. (2003) while Gupta Joshi (2012) made a preliminary quantitative analysis of vegetation structure covering a few sites in the lateritic zone. Kushwaha and Nandy (2012) compared species diversity and community structure of sal forests under different rainfall regimes. Pandit (2011) documented about sacred groves of West Medinipur district. No reports are available on vegetation analysis of Garhjungle sacred forests.
The objective of the present study is to analyze the vegetation structure and species diversity pattern of a sacred forest from lateritic zone which in turn will help to control the forest structure by plantation and better management of the forest flora.
Conclusion
The results of present study indicated a young or regenerating population of tree species. Future work will compare the vegetation structure of this sacred forest with adjacent forests under different management regimes. It is generally believed and supported by published reports that sacred forests are better protected and managed owing to their religious significance and harbour richer plant diversity than other forests. However, comparison with results from other sacred forests indicated lower species richness, diversity as well as basal area in the Garhjungle sacred forests. The health of Garhjungle sacred forests is deteriorating due to various anthropogenic disturbances such as grazing, extraction of fuel wood, collection of various NTFP, etc. apart from the periodic man made fires. Therefore further conservation efforts are immediately needed to curb the anthropogenic disturbances.